The purpose of the proposed research is to understand the neurocognitive processes that underlie human recognition memory. Recognition is supported by processes that are sensitive to the general familiarity of stimuli as well as by processes enabling the recollection of specific information. Behavioral research suggests that these processes can be dissociated by manipulating variables that differentially affect recollection and familiarity, but the characteristics of the underlying brain processes have yet to be reliably differentiated. Based on preliminary results, the proposed research investigates the hypothesis that recollection and familiarity can be differentiated with event-related brain potentials (ERPs). Early (300-500 ms) frontal ERP effects are modulated by stimulus familiarity, whereas later (400-800 ms) parietal ERP effects are related to recollection. The general aim of the proposed research is to better specify the relationship between the hypothesized ERP familiarity and recollection effects, contemporary theories of familiarity and recollection, and behavioral recognition memory performance. The first specific aim is to delineate the temporal correspondence between the hypothesized ERP familiarity and recollection effects and behavioral recognition memory performance. The second specific aim is to electrophysiologically replicate several behavioral dissociations between recollection and familiarity that have been previously reported. The third specific aim is to use ERPs to examine empirical phenomena that are central to current cognitive theorizing about recognition memory. The present research will advance our understanding of the processes that underlie human memory at both the cognitive and neural level. Our understanding of the brain mechanisms of memory will be advanced by characterizing the timing and anatomical separability of these processes. Our understanding of the cognitive processes of recollection and familiarity will be enhanced by establishing measures of brain electrical activity that reliably differentiate between these processes, by manipulating psychological variables known to affect recognition, and by observing how these variables differentially affect the electrophysiological measures of recollection and familiarity. Future studies can apply these methods to the investigation of memory impairments associated with normal aging, psychiatric disorders, and neurological damage.